225g unsalted butter, very soft
225g caster sugar
1 teaspoon vanilla extract
4 large eggs
200g self raising flour
3-4 tablespoons milk
2x 21cm sandwich tins, buttered
preheat oven to 180 degrees/gas mark 4. line tins.
cream butter and sugar, add the vanilla and then the eggs, one at a time, adding a spoonful of flour between each. Fold in the rest of the flour and the cornflour then when all incorporated add a little milk at the end as needed.
Pour into tins and bake for about 25 mins.
Leave in tins on wire rack for 10 mins before turning out and leaving to cool completely.
or you can do it in a food processor:
put everyting in (plus 1 teaspoon of baking powder) except the milk and process till you have a smooth batter. Then pulse, pouring the milk gradually through the funnel till it's a soft, gloopy consistency.